1. Field of the Invention
The present invention relates to a piezoelectric device to be installed in a filter circuit, an oscillation circuit or the like.
2. Description of Related Art
FIG. 4 shows a conventional piezoelectric device. The piezoelectric device comprises a piezoelectric substrate 31, an insulating case 35 having a recess 35a and a lid 36.
The piezoelectric substrate 31 has oscillation electrodes 32a and 32b on its front side and back side respectively. The piezoelectric substrate 31 is horizontally laid in the recess 35a. The oscillation electrodes 32a and 32b have contact portions 33a and 33b at their ends, and the contact portions 33a and 33b are electrically connected with inner electrodes 37a and 37b respectively by a conductive adhesive 34. The lid 36 covers an opening of the case 35 and is fixed thereon by an adhesive. The piezoelectric device has outer electrodes 38a, 38b and 38c thereon. The electrodes 38a and 38b are formed on the end portions, and the electrode 38c is formed on the center portion. The outer electrodes 38a and 38b are electrically connected with the inner electrodes 37a and 37b respectively.
In connecting the contact portions 33a and 33b with the inner electrodes 37a and 37b by the conductive adhesive 34, the conductive adhesive 34 must be put on the back side of the piezoelectric substrate 31 as well as the front side thereof because the contact portions 33a and 33b are on the front side and the back side. Conventionally, the following method has been adopted in order to put a conductive adhesive on the back side of the substrate 31 as well. The inner electrodes 37a and 37b are coated with a conductive paste in advance, and the piezoelectric substrate 31 is laid between the electrodes 37a and 37b. Further, the end portions of the substrate 31 are coated with the conductive paste. In this method, the coating process is repeated twice, and the number of processes is increased. Accordingly, the production cost is raised.